This invention relates to an improvement in a process for forming a color filter according to a silver salt photographic process.
A process for forming a color filter using a coupler-in-developer type color developing process is described in Japanese Patent Application No. 78313/78 (corresponding to U.S. patent application Ser. No. 52,704, filed June 28, 1979, now U.S. Pat. No. 4,271,246) by some of the same inventors herein. This color filter-forming process fundamentally comprises subjecting to a first patternwise exposure a black-and-white silver halide emulsion layer of a photographic material comprising a support having thereon at least one black-and-white emulsion layer, developing the photographic material with a coupler-in-developer color-developing process wherein the color developer contains a color coupler to form a pattern containing the first color dye and, after final color development, conducting a silver-removing processing. Further, after formation of the first color pattern, similar steps are repeated to form another pattern containing a second color dye, and so on, thus forming at least two color patterns.
This process provides the advantage that a color filter can be obtained much less expensively as compared to known color filters using an interference filter or those obtained by dyeing a relief of a high molecular weight polymer material with a dye.
However, color filters obtained by this process described in Japanese Patent Application No. 78313/78 have the defect that they have spectral characteristics which are not as sharp as those of known interference filters or the like. That is, as is shown in FIG. 1, when transmittance is plotted as the ordinate and wavelength as the abscissa, the change in transmittance of, for example, a yellow filter over the transmittance range of from about 0% to about 90% is not as sharp as indicated by curve A.